PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 17025367

Macromolecular assemblies based on coupled inclusion complex and electrostatic interactions.

Virginie Burckbuchler·Valérie Boutant·Véronique Wintgens·Catherine Amiel
View original source ↗Export metadata ↓

Abstract

Macromolecular assemblies are elaborated by mixing beta-cyclodextrin-containing polymer (polybetaCD), dextran sulfate polyanion (NaDxS), and cationic amphiphiles which are adamantane derivatives (Ada1 or Ada2) in aqueous medium. These components are assembled via coupled inclusion complex interactions (adamantyl group with cyclodextrin cavity) and electrostatic attractive interactions (positive charges of Ada with negative charge of NaDxS). The structural properties are studied by viscometry and small angle neutron scattering. Ternary aggregates with larger size and lower compacities are observed as the cation concentration is increased, until phase separation occurs. The results are in good agreement with a core-shell association mechanism, the core being made of one polybetaCD chain, the shell of NaDxS chains, and the Ada amphiphiles being distributed more or less homogeneously inside the cyclodextrin cavities. The nature of the Ada counterions has a strong influence on the association as Ada1 with I(-) counterions give smaller and less compact aggregates than Ada2 with Br(-) counterions.

Explore related subjects

Binding, CompetitiveBiotechnologyCyclodextrinsDextran SulfateElectrochemistryIonsKineticsMacromolecular SubstancesMicroscopy, FluorescenceModels, ChemicalNeutronsPolymersScattering, RadiationStatic Electricitybeta-CyclodextrinsJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Virginie Burckbuchler, Valérie Boutant, Véronique Wintgens, Catherine Amiel. 2006. Macromolecular assemblies based on coupled inclusion complex and electrostatic interactions.. https://doi.org/10.1021/bm060523k

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Co-immobilization of different enzyme activities to non-woven polyester surfaces.

Co-immobilization was applied to combine complementary enzyme reactions. Therefore, trypsin was co-immobilized together with both, lipase and alpha-amylase, onto the surface of non-woven polyester material. The progress of the immobilization reaction was directly monitored by investigating covalent fixation of the enzymes to the polyester flees using (1)H-MAS-NMR. Co-immobilization of the different types of enzymes to the polyester support showed retained enzymatic activity. However, a competition of binding to the support was observed. Increasing amounts of one type of enzyme reduced the degree of immobilization for the other type. In order to investigate the distribution of trypsin and alpha-amylase on the polyester support, the flees was treated with a mixture of rhodamine isothiocyanate labeled with anti-trypsin antibodies and fluorescein isothiocyanate labeled with anti-alpha-amylase antibodies. Using fluorescence microscopy, the co-immobilization was analyzed by selective excitation of both chromophores at 480 and 530 nm, respectively. In addition, fluorescence spectroscopy was applied by direct labeling of trypsin and lipase prior to co-immobilization to the polyester support. A special prism of plexiglass was constructed, which fit into a 10 x 10 mm fluorescence cuvette in that way that a diagonal plane was formed within the cuvette. The non-woven support was fixed in the cuvette and fluorescence spectra were obtained to characterize the amount of different enzymes linked to the support. Using FRET it was demonstrated that a uniform distribution of the various enzyme species was achieved, where the different enzyme activities are bound on the support in close neighborhood to one another.

Binding, Competitive↗
PubMed2007

Scintillation proximity assay as a high-throughput method to identify slowly dissociating nonpeptide ligand binding to the GnRH receptor.

Many nonpeptide antagonists of the gonadotropin-releasing hormone (GnRH) receptor, as well as other drug targets, possess a broad range of dissociation kinetic rate constants. Current methods to accurately define kinetic rate parameters such as K(on) and K(off) are time and labor intensive, prompting the development of a screening assay to identify slowly dissociating compounds for follow-up rate constant determination. The authors measured inhibition binding constants (K(i)) for GnRH receptor antagonists after 30 min and 10 h of incubation and observed several compounds with markedly decreased K(i) values over time (Ki(30 min)/Ki(10 h) > 6). They used scintillation proximity assay technology to perform these binding experiments because this homogeneous assay does not have a fixed termination end point as does filtration binding, permitting successive readings to be taken from the same assay plate over an extended period of time. They also used a quantitative method of kinetic rate analysis to confirm that a large disparity between a compound's K(i) value at 30 min and 10 h could identify compounds that dissociate slowly. Thus, the K(i) ratio can be used to screen for and select compounds to test using more quantitative, albeit lower throughput methods to accurately define kinetic rate constants.

Binding, Competitive↗
PubMed2007

The anomalous behaviour of exogenous 25-hydroxyvitamin D in competitive binding assays.

The Vitamin D International External Quality Assessment Scheme (DEQAS) was established in 1989 to monitor the performance of assays for 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (I,25(OH)(2)D). This is achieved through the quarterly distribution of five samples of human serum. Results are used to calculate an All-Laboratory Trimmed Mean and a Method Mean for each of the methods used by participants. In July 2005, participants were asked to assay serum to which 50.9 nmol of either 25-OHD(3) or 25-OHD(2) had been added as ethanolic solutions. The final concentration of ethanol in the serum was 0.7%. The distribution also included a sample of the original serum (OS) containing 0.7% pure ethanol. The percentage recoveries of exogenous 25-OHD(3) (R1) and 25-OHD(2) (R2) were calculated for each method. Results (OS nM, R1 and R2) were as follows: DiaSorin RIA (n=53); 39.2, 82.1%, 83.3%, DiaSorin Liason (n=16); 36.8, 81.4%, 88.6%, IDS RIA (n=21); 36.4, 54.2%, 29.1%, IDS OCTEIA (n=16); 47.3, 78.8%, 56.4%, Nichols Advantage (n=21); 58.9, 46.4%, 43.2%, HPLC (n=9); 42.6, 112.2%, 97.1%, LC-MS (n=4); 34.0, 111.5%, 118.1%. The IDS RIA and Nichols assays gave unexpectedly low recoveries. This does not appear to be a calibration problem or the effect of ethanol.

Binding, Competitive↗